From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751611AbdBWPzf (ORCPT ); Thu, 23 Feb 2017 10:55:35 -0500 Received: from foss.arm.com ([217.140.101.70]:56130 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751245AbdBWPzd (ORCPT ); Thu, 23 Feb 2017 10:55:33 -0500 Subject: Re: [PATCH/RFC 0/6] PSCI: Fix non-PMIC wake-up if SYSTEM_SUSPEND cuts power To: Geert Uytterhoeven References: <1487622809-25127-1-git-send-email-geert+renesas@glider.be> <94167d3a-e005-3af0-d290-a1086684d570@arm.com> <3c8b3f2d-8604-f999-4208-a82f171b64f2@arm.com> <1975396.x0czmkNPOW@aspire.rjw.lan> <35840771-e16f-d6fe-3a89-1b3f51f4a8f3@arm.com> Cc: Sudeep Holla , "Rafael J. Wysocki" , Geert Uytterhoeven , Lorenzo Pieralisi , Mark Rutland , Lina Iyer , John Stultz , Thomas Gleixner , Len Brown , Pavel Machek , Rob Herring , Magnus Damm , "devicetree@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , Linux-Renesas , Linux PM list , "linux-kernel@vger.kernel.org" From: Sudeep Holla Organization: ARM Message-ID: Date: Thu, 23 Feb 2017 15:53:14 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 23/02/17 15:26, Geert Uytterhoeven wrote: > Hi Sudeep, > > On Wed, Feb 22, 2017 at 3:32 PM, Sudeep Holla wrote: >> On 22/02/17 13:38, Geert Uytterhoeven wrote: >>> On Wed, Feb 22, 2017 at 12:03 PM, Sudeep Holla wrote: >>>> On 22/02/17 01:14, Rafael J. Wysocki wrote: >>>>> On Tuesday, February 21, 2017 06:45:13 PM Sudeep Holla wrote: >>>> Geert, so far you have failed to explain what's different from the new >>>> state you are adding and the existing s2idle. >>> >>> I did explain, cfr.: >>> 1. The power consumption figures in the cover letter: >>> - shallow: 8.4 W 6.2 W (secondary CPU cores off) >> >> That's because your CPU_SUSPEND implementation is incomplete. You can >> enter the same state as secondary CPU core off even with idle. It's just >> that we can save by not entering and exiting the CPU hotplug state >> machine. So this "shallow" state can be achieved if your CPU_SUSPEND >> implements that state. > > Does that include power areas? > OK, I first I didn't understand what you are referring here but I see some reference further in the email. >>> 2. The description for patch 3/6: >>> As secondary CPU cores are taken offline, "shallow" suspend mode saves >>> slightly more power than "s2idle", but less than "deep" suspend mode. >>> However, unlike "deep" suspend mode, "shallow" suspend mode can be used >>> regardless of the presence of support for PSCI_SYSTEM_SUSPEND, which is >>> an optional API in PSCI v1.0. >> >> Yes I understood that, you need to add an extra idle states to get that >> shallow state. We have discussed this in past to depth. On ARM64/PSCI, >> we will that support "shallow" system suspend mode which can't be >> defined generically. Also we can support this shallow state with s2idle. >> >> Your system probably not supporting all the CPU idle states. E.g.: it >> may just support CPU ON/OFF/RET and not cluster ON/OFF/RET. Please add >> that state to CPU_SUSPEND implementation in the firmware. > > I can find CPU_ON and CPU_OFF in the PSCI specification, but not > CPU_RET? > No, they were just examples of idle states that CPU_SUSPEND call might support based on what h/w can support on a particular platform. > How is the cluster ON/OFF/RET called exactly? I can't find any CLUSTER_* > calls in the PSCI specification. > CPU_SUSPEND with different parameters, just look at the details on suspend parameters in Section 5.4.2 CPU_SUSPEND parameters: power_state > From a quick glance in the PSCI sources, there's some support for powering > down clusters. > Yes, the above section should provide some insight on the same. >>> Perhaps, I didn't make myself clear. Let's summarize: >>> 1. On Renesas R-Car Gen3 platforms, PSCI SYSTEM_SUSPEND is implemented, >> >> OK got that. >> >>> 2. On these platforms, PSCI SYSTEM_SUSPEND powers down the SoC, and supports >>> wake-up from PMIC only, >> >> OK >> >>> 3. If the user wants to use a different wake-up source, these other >>> wake-up sources fail to wake up the system from PSCI SYSTEM_SUSPEND. >> >> In that case don't enter PSCI SYSTEM_SUSPEND > > Or prevent the system from doing that... > Agreed. >>> 4. Patch 3/6 adds a new "shallow" state, as it allows to save more >>> power (the difference may be due to suboptimal cpuidle platform support on R-Car Gen3, though), >> >> Why can't you do that in s2idle mode. Please give me the difference >> between your shallow state and s2idle state, not just power numbers >> but the actual state of CPUs and the devices in the system. > > From the Linux side, there's not much difference, except that the secondary > CPU cores are disabled. As that is handled by PSCI, the difference may be > in the PSCI implementation. I will have to check that... > Yes it's better to check. I am afraid that both these states will be same if PSCI implementation is correct and hence we don't want to support standby suspend mode. > On these SoCs, the individual CPU cores and the SCU/L2 are in separate > (nested) power areas. Perhaps these power areas are turned off when > disabling the CPU cores, but not when suspending them. > Yes that's what I suspect and hence I said it's incomplete implementation of CPU_SUSPEND >>> E.g. on non-PSCI platforms with an Ethernet driver that supports >>> Wake-on-LAN, I can do: >>> >>> ethtool -s eth0 wol g >>> echo mem > /sys/power/state >>> >>> and be sure that the system can be woken up by sending a WoL MagicPacket. >> >> Still possible with s2idle if CPU_SUSPEND is correctly implemented by >> the platform. > > Sure. But not automatic, as it needs fiddling with mem_sleep. > Yes that's true form any thing other than "deep" state. i.e. s2idle or standby. If you are OK to choose standby why not s2idle ? >>> On PSCI systems, the above may work, or may not work. And there's no way to >>> find out (in an automated way) whether it will work or not. >>> >>> If it doesn't work, the user has to configure his system (manually) to >>> not use "mem" state. >>> Since v4.10-rc1, that can be done using e.g. >>> >>> echo s2idle > /sys/power/mem_sleep >>> >>> and my patches make that automatic (for a new "shallow" state instead >>> of "s2idle", though). >> >> How is that ? If "deep" is available as in your case too, why will >> shallow become default. IIUC the user still have to write "shallow" >> to mem_sleep. > > After patch 4, if needed (DT property + extra wake-up sources configured), > psci_system_suspend_enter() will call cpu_do_idle() instead of > psci_system_suspend(). No need to fiddle with mem_sleep manually. > I understand your intentions and but I have NACKed it with sufficient reasoning. I don't want to repeat them again here. >> Does this platform use generic arm64 DT cpuidle driver ? I don't see so >> from the DT. > > I think that task isn't complete yet. > So, all these hacks are just to cope up with that ? Sorry that's non-sense. Working around a firmware bug is different from working around the incomplete firmware implementation. We may consider former but for me latter is just insane. -- Regards, Sudeep From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sudeep Holla Subject: Re: [PATCH/RFC 0/6] PSCI: Fix non-PMIC wake-up if SYSTEM_SUSPEND cuts power Date: Thu, 23 Feb 2017 15:53:14 +0000 Message-ID: References: <1487622809-25127-1-git-send-email-geert+renesas@glider.be> <94167d3a-e005-3af0-d290-a1086684d570@arm.com> <3c8b3f2d-8604-f999-4208-a82f171b64f2@arm.com> <1975396.x0czmkNPOW@aspire.rjw.lan> <35840771-e16f-d6fe-3a89-1b3f51f4a8f3@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: Geert Uytterhoeven Cc: Mark Rutland , Len Brown , Lorenzo Pieralisi , Geert Uytterhoeven , "devicetree@vger.kernel.org" , Magnus Damm , Linux PM list , "Rafael J. Wysocki" , "linux-kernel@vger.kernel.org" , Linux-Renesas , Rob Herring , John Stultz , "linux-arm-kernel@lists.infradead.org" , Pavel Machek , Sudeep Holla , Thomas Gleixner , Lina Iyer List-Id: devicetree@vger.kernel.org On 23/02/17 15:26, Geert Uytterhoeven wrote: > Hi Sudeep, > > On Wed, Feb 22, 2017 at 3:32 PM, Sudeep Holla wrote: >> On 22/02/17 13:38, Geert Uytterhoeven wrote: >>> On Wed, Feb 22, 2017 at 12:03 PM, Sudeep Holla wrote: >>>> On 22/02/17 01:14, Rafael J. Wysocki wrote: >>>>> On Tuesday, February 21, 2017 06:45:13 PM Sudeep Holla wrote: >>>> Geert, so far you have failed to explain what's different from the new >>>> state you are adding and the existing s2idle. >>> >>> I did explain, cfr.: >>> 1. The power consumption figures in the cover letter: >>> - shallow: 8.4 W 6.2 W (secondary CPU cores off) >> >> That's because your CPU_SUSPEND implementation is incomplete. You can >> enter the same state as secondary CPU core off even with idle. It's just >> that we can save by not entering and exiting the CPU hotplug state >> machine. So this "shallow" state can be achieved if your CPU_SUSPEND >> implements that state. > > Does that include power areas? > OK, I first I didn't understand what you are referring here but I see some reference further in the email. >>> 2. The description for patch 3/6: >>> As secondary CPU cores are taken offline, "shallow" suspend mode saves >>> slightly more power than "s2idle", but less than "deep" suspend mode. >>> However, unlike "deep" suspend mode, "shallow" suspend mode can be used >>> regardless of the presence of support for PSCI_SYSTEM_SUSPEND, which is >>> an optional API in PSCI v1.0. >> >> Yes I understood that, you need to add an extra idle states to get that >> shallow state. We have discussed this in past to depth. On ARM64/PSCI, >> we will that support "shallow" system suspend mode which can't be >> defined generically. Also we can support this shallow state with s2idle. >> >> Your system probably not supporting all the CPU idle states. E.g.: it >> may just support CPU ON/OFF/RET and not cluster ON/OFF/RET. Please add >> that state to CPU_SUSPEND implementation in the firmware. > > I can find CPU_ON and CPU_OFF in the PSCI specification, but not > CPU_RET? > No, they were just examples of idle states that CPU_SUSPEND call might support based on what h/w can support on a particular platform. > How is the cluster ON/OFF/RET called exactly? I can't find any CLUSTER_* > calls in the PSCI specification. > CPU_SUSPEND with different parameters, just look at the details on suspend parameters in Section 5.4.2 CPU_SUSPEND parameters: power_state > From a quick glance in the PSCI sources, there's some support for powering > down clusters. > Yes, the above section should provide some insight on the same. >>> Perhaps, I didn't make myself clear. Let's summarize: >>> 1. On Renesas R-Car Gen3 platforms, PSCI SYSTEM_SUSPEND is implemented, >> >> OK got that. >> >>> 2. On these platforms, PSCI SYSTEM_SUSPEND powers down the SoC, and supports >>> wake-up from PMIC only, >> >> OK >> >>> 3. If the user wants to use a different wake-up source, these other >>> wake-up sources fail to wake up the system from PSCI SYSTEM_SUSPEND. >> >> In that case don't enter PSCI SYSTEM_SUSPEND > > Or prevent the system from doing that... > Agreed. >>> 4. Patch 3/6 adds a new "shallow" state, as it allows to save more >>> power (the difference may be due to suboptimal cpuidle platform support on R-Car Gen3, though), >> >> Why can't you do that in s2idle mode. Please give me the difference >> between your shallow state and s2idle state, not just power numbers >> but the actual state of CPUs and the devices in the system. > > From the Linux side, there's not much difference, except that the secondary > CPU cores are disabled. As that is handled by PSCI, the difference may be > in the PSCI implementation. I will have to check that... > Yes it's better to check. I am afraid that both these states will be same if PSCI implementation is correct and hence we don't want to support standby suspend mode. > On these SoCs, the individual CPU cores and the SCU/L2 are in separate > (nested) power areas. Perhaps these power areas are turned off when > disabling the CPU cores, but not when suspending them. > Yes that's what I suspect and hence I said it's incomplete implementation of CPU_SUSPEND >>> E.g. on non-PSCI platforms with an Ethernet driver that supports >>> Wake-on-LAN, I can do: >>> >>> ethtool -s eth0 wol g >>> echo mem > /sys/power/state >>> >>> and be sure that the system can be woken up by sending a WoL MagicPacket. >> >> Still possible with s2idle if CPU_SUSPEND is correctly implemented by >> the platform. > > Sure. But not automatic, as it needs fiddling with mem_sleep. > Yes that's true form any thing other than "deep" state. i.e. s2idle or standby. If you are OK to choose standby why not s2idle ? >>> On PSCI systems, the above may work, or may not work. And there's no way to >>> find out (in an automated way) whether it will work or not. >>> >>> If it doesn't work, the user has to configure his system (manually) to >>> not use "mem" state. >>> Since v4.10-rc1, that can be done using e.g. >>> >>> echo s2idle > /sys/power/mem_sleep >>> >>> and my patches make that automatic (for a new "shallow" state instead >>> of "s2idle", though). >> >> How is that ? If "deep" is available as in your case too, why will >> shallow become default. IIUC the user still have to write "shallow" >> to mem_sleep. > > After patch 4, if needed (DT property + extra wake-up sources configured), > psci_system_suspend_enter() will call cpu_do_idle() instead of > psci_system_suspend(). No need to fiddle with mem_sleep manually. > I understand your intentions and but I have NACKed it with sufficient reasoning. I don't want to repeat them again here. >> Does this platform use generic arm64 DT cpuidle driver ? I don't see so >> from the DT. > > I think that task isn't complete yet. > So, all these hacks are just to cope up with that ? Sorry that's non-sense. Working around a firmware bug is different from working around the incomplete firmware implementation. We may consider former but for me latter is just insane. -- Regards, Sudeep From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from foss.arm.com ([217.140.101.70]:56130 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751245AbdBWPzd (ORCPT ); Thu, 23 Feb 2017 10:55:33 -0500 Subject: Re: [PATCH/RFC 0/6] PSCI: Fix non-PMIC wake-up if SYSTEM_SUSPEND cuts power To: Geert Uytterhoeven References: <1487622809-25127-1-git-send-email-geert+renesas@glider.be> <94167d3a-e005-3af0-d290-a1086684d570@arm.com> <3c8b3f2d-8604-f999-4208-a82f171b64f2@arm.com> <1975396.x0czmkNPOW@aspire.rjw.lan> <35840771-e16f-d6fe-3a89-1b3f51f4a8f3@arm.com> Cc: Sudeep Holla , "Rafael J. Wysocki" , Geert Uytterhoeven , Lorenzo Pieralisi , Mark Rutland , Lina Iyer , John Stultz , Thomas Gleixner , Len Brown , Pavel Machek , Rob Herring , Magnus Damm , "devicetree@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , Linux-Renesas , Linux PM list , "linux-kernel@vger.kernel.org" From: Sudeep Holla Message-ID: Date: Thu, 23 Feb 2017 15:53:14 +0000 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-renesas-soc-owner@vger.kernel.org List-ID: On 23/02/17 15:26, Geert Uytterhoeven wrote: > Hi Sudeep, > > On Wed, Feb 22, 2017 at 3:32 PM, Sudeep Holla wrote: >> On 22/02/17 13:38, Geert Uytterhoeven wrote: >>> On Wed, Feb 22, 2017 at 12:03 PM, Sudeep Holla wrote: >>>> On 22/02/17 01:14, Rafael J. Wysocki wrote: >>>>> On Tuesday, February 21, 2017 06:45:13 PM Sudeep Holla wrote: >>>> Geert, so far you have failed to explain what's different from the new >>>> state you are adding and the existing s2idle. >>> >>> I did explain, cfr.: >>> 1. The power consumption figures in the cover letter: >>> - shallow: 8.4 W 6.2 W (secondary CPU cores off) >> >> That's because your CPU_SUSPEND implementation is incomplete. You can >> enter the same state as secondary CPU core off even with idle. It's just >> that we can save by not entering and exiting the CPU hotplug state >> machine. So this "shallow" state can be achieved if your CPU_SUSPEND >> implements that state. > > Does that include power areas? > OK, I first I didn't understand what you are referring here but I see some reference further in the email. >>> 2. The description for patch 3/6: >>> As secondary CPU cores are taken offline, "shallow" suspend mode saves >>> slightly more power than "s2idle", but less than "deep" suspend mode. >>> However, unlike "deep" suspend mode, "shallow" suspend mode can be used >>> regardless of the presence of support for PSCI_SYSTEM_SUSPEND, which is >>> an optional API in PSCI v1.0. >> >> Yes I understood that, you need to add an extra idle states to get that >> shallow state. We have discussed this in past to depth. On ARM64/PSCI, >> we will that support "shallow" system suspend mode which can't be >> defined generically. Also we can support this shallow state with s2idle. >> >> Your system probably not supporting all the CPU idle states. E.g.: it >> may just support CPU ON/OFF/RET and not cluster ON/OFF/RET. Please add >> that state to CPU_SUSPEND implementation in the firmware. > > I can find CPU_ON and CPU_OFF in the PSCI specification, but not > CPU_RET? > No, they were just examples of idle states that CPU_SUSPEND call might support based on what h/w can support on a particular platform. > How is the cluster ON/OFF/RET called exactly? I can't find any CLUSTER_* > calls in the PSCI specification. > CPU_SUSPEND with different parameters, just look at the details on suspend parameters in Section 5.4.2 CPU_SUSPEND parameters: power_state > From a quick glance in the PSCI sources, there's some support for powering > down clusters. > Yes, the above section should provide some insight on the same. >>> Perhaps, I didn't make myself clear. Let's summarize: >>> 1. On Renesas R-Car Gen3 platforms, PSCI SYSTEM_SUSPEND is implemented, >> >> OK got that. >> >>> 2. On these platforms, PSCI SYSTEM_SUSPEND powers down the SoC, and supports >>> wake-up from PMIC only, >> >> OK >> >>> 3. If the user wants to use a different wake-up source, these other >>> wake-up sources fail to wake up the system from PSCI SYSTEM_SUSPEND. >> >> In that case don't enter PSCI SYSTEM_SUSPEND > > Or prevent the system from doing that... > Agreed. >>> 4. Patch 3/6 adds a new "shallow" state, as it allows to save more >>> power (the difference may be due to suboptimal cpuidle platform support on R-Car Gen3, though), >> >> Why can't you do that in s2idle mode. Please give me the difference >> between your shallow state and s2idle state, not just power numbers >> but the actual state of CPUs and the devices in the system. > > From the Linux side, there's not much difference, except that the secondary > CPU cores are disabled. As that is handled by PSCI, the difference may be > in the PSCI implementation. I will have to check that... > Yes it's better to check. I am afraid that both these states will be same if PSCI implementation is correct and hence we don't want to support standby suspend mode. > On these SoCs, the individual CPU cores and the SCU/L2 are in separate > (nested) power areas. Perhaps these power areas are turned off when > disabling the CPU cores, but not when suspending them. > Yes that's what I suspect and hence I said it's incomplete implementation of CPU_SUSPEND >>> E.g. on non-PSCI platforms with an Ethernet driver that supports >>> Wake-on-LAN, I can do: >>> >>> ethtool -s eth0 wol g >>> echo mem > /sys/power/state >>> >>> and be sure that the system can be woken up by sending a WoL MagicPacket. >> >> Still possible with s2idle if CPU_SUSPEND is correctly implemented by >> the platform. > > Sure. But not automatic, as it needs fiddling with mem_sleep. > Yes that's true form any thing other than "deep" state. i.e. s2idle or standby. If you are OK to choose standby why not s2idle ? >>> On PSCI systems, the above may work, or may not work. And there's no way to >>> find out (in an automated way) whether it will work or not. >>> >>> If it doesn't work, the user has to configure his system (manually) to >>> not use "mem" state. >>> Since v4.10-rc1, that can be done using e.g. >>> >>> echo s2idle > /sys/power/mem_sleep >>> >>> and my patches make that automatic (for a new "shallow" state instead >>> of "s2idle", though). >> >> How is that ? If "deep" is available as in your case too, why will >> shallow become default. IIUC the user still have to write "shallow" >> to mem_sleep. > > After patch 4, if needed (DT property + extra wake-up sources configured), > psci_system_suspend_enter() will call cpu_do_idle() instead of > psci_system_suspend(). No need to fiddle with mem_sleep manually. > I understand your intentions and but I have NACKed it with sufficient reasoning. I don't want to repeat them again here. >> Does this platform use generic arm64 DT cpuidle driver ? I don't see so >> from the DT. > > I think that task isn't complete yet. > So, all these hacks are just to cope up with that ? Sorry that's non-sense. Working around a firmware bug is different from working around the incomplete firmware implementation. We may consider former but for me latter is just insane. -- Regards, Sudeep From mboxrd@z Thu Jan 1 00:00:00 1970 From: sudeep.holla@arm.com (Sudeep Holla) Date: Thu, 23 Feb 2017 15:53:14 +0000 Subject: [PATCH/RFC 0/6] PSCI: Fix non-PMIC wake-up if SYSTEM_SUSPEND cuts power In-Reply-To: References: <1487622809-25127-1-git-send-email-geert+renesas@glider.be> <94167d3a-e005-3af0-d290-a1086684d570@arm.com> <3c8b3f2d-8604-f999-4208-a82f171b64f2@arm.com> <1975396.x0czmkNPOW@aspire.rjw.lan> <35840771-e16f-d6fe-3a89-1b3f51f4a8f3@arm.com> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 23/02/17 15:26, Geert Uytterhoeven wrote: > Hi Sudeep, > > On Wed, Feb 22, 2017 at 3:32 PM, Sudeep Holla wrote: >> On 22/02/17 13:38, Geert Uytterhoeven wrote: >>> On Wed, Feb 22, 2017 at 12:03 PM, Sudeep Holla wrote: >>>> On 22/02/17 01:14, Rafael J. Wysocki wrote: >>>>> On Tuesday, February 21, 2017 06:45:13 PM Sudeep Holla wrote: >>>> Geert, so far you have failed to explain what's different from the new >>>> state you are adding and the existing s2idle. >>> >>> I did explain, cfr.: >>> 1. The power consumption figures in the cover letter: >>> - shallow: 8.4 W 6.2 W (secondary CPU cores off) >> >> That's because your CPU_SUSPEND implementation is incomplete. You can >> enter the same state as secondary CPU core off even with idle. It's just >> that we can save by not entering and exiting the CPU hotplug state >> machine. So this "shallow" state can be achieved if your CPU_SUSPEND >> implements that state. > > Does that include power areas? > OK, I first I didn't understand what you are referring here but I see some reference further in the email. >>> 2. The description for patch 3/6: >>> As secondary CPU cores are taken offline, "shallow" suspend mode saves >>> slightly more power than "s2idle", but less than "deep" suspend mode. >>> However, unlike "deep" suspend mode, "shallow" suspend mode can be used >>> regardless of the presence of support for PSCI_SYSTEM_SUSPEND, which is >>> an optional API in PSCI v1.0. >> >> Yes I understood that, you need to add an extra idle states to get that >> shallow state. We have discussed this in past to depth. On ARM64/PSCI, >> we will that support "shallow" system suspend mode which can't be >> defined generically. Also we can support this shallow state with s2idle. >> >> Your system probably not supporting all the CPU idle states. E.g.: it >> may just support CPU ON/OFF/RET and not cluster ON/OFF/RET. Please add >> that state to CPU_SUSPEND implementation in the firmware. > > I can find CPU_ON and CPU_OFF in the PSCI specification, but not > CPU_RET? > No, they were just examples of idle states that CPU_SUSPEND call might support based on what h/w can support on a particular platform. > How is the cluster ON/OFF/RET called exactly? I can't find any CLUSTER_* > calls in the PSCI specification. > CPU_SUSPEND with different parameters, just look at the details on suspend parameters in Section 5.4.2 CPU_SUSPEND parameters: power_state > From a quick glance in the PSCI sources, there's some support for powering > down clusters. > Yes, the above section should provide some insight on the same. >>> Perhaps, I didn't make myself clear. Let's summarize: >>> 1. On Renesas R-Car Gen3 platforms, PSCI SYSTEM_SUSPEND is implemented, >> >> OK got that. >> >>> 2. On these platforms, PSCI SYSTEM_SUSPEND powers down the SoC, and supports >>> wake-up from PMIC only, >> >> OK >> >>> 3. If the user wants to use a different wake-up source, these other >>> wake-up sources fail to wake up the system from PSCI SYSTEM_SUSPEND. >> >> In that case don't enter PSCI SYSTEM_SUSPEND > > Or prevent the system from doing that... > Agreed. >>> 4. Patch 3/6 adds a new "shallow" state, as it allows to save more >>> power (the difference may be due to suboptimal cpuidle platform support on R-Car Gen3, though), >> >> Why can't you do that in s2idle mode. Please give me the difference >> between your shallow state and s2idle state, not just power numbers >> but the actual state of CPUs and the devices in the system. > > From the Linux side, there's not much difference, except that the secondary > CPU cores are disabled. As that is handled by PSCI, the difference may be > in the PSCI implementation. I will have to check that... > Yes it's better to check. I am afraid that both these states will be same if PSCI implementation is correct and hence we don't want to support standby suspend mode. > On these SoCs, the individual CPU cores and the SCU/L2 are in separate > (nested) power areas. Perhaps these power areas are turned off when > disabling the CPU cores, but not when suspending them. > Yes that's what I suspect and hence I said it's incomplete implementation of CPU_SUSPEND >>> E.g. on non-PSCI platforms with an Ethernet driver that supports >>> Wake-on-LAN, I can do: >>> >>> ethtool -s eth0 wol g >>> echo mem > /sys/power/state >>> >>> and be sure that the system can be woken up by sending a WoL MagicPacket. >> >> Still possible with s2idle if CPU_SUSPEND is correctly implemented by >> the platform. > > Sure. But not automatic, as it needs fiddling with mem_sleep. > Yes that's true form any thing other than "deep" state. i.e. s2idle or standby. If you are OK to choose standby why not s2idle ? >>> On PSCI systems, the above may work, or may not work. And there's no way to >>> find out (in an automated way) whether it will work or not. >>> >>> If it doesn't work, the user has to configure his system (manually) to >>> not use "mem" state. >>> Since v4.10-rc1, that can be done using e.g. >>> >>> echo s2idle > /sys/power/mem_sleep >>> >>> and my patches make that automatic (for a new "shallow" state instead >>> of "s2idle", though). >> >> How is that ? If "deep" is available as in your case too, why will >> shallow become default. IIUC the user still have to write "shallow" >> to mem_sleep. > > After patch 4, if needed (DT property + extra wake-up sources configured), > psci_system_suspend_enter() will call cpu_do_idle() instead of > psci_system_suspend(). No need to fiddle with mem_sleep manually. > I understand your intentions and but I have NACKed it with sufficient reasoning. I don't want to repeat them again here. >> Does this platform use generic arm64 DT cpuidle driver ? I don't see so >> from the DT. > > I think that task isn't complete yet. > So, all these hacks are just to cope up with that ? Sorry that's non-sense. Working around a firmware bug is different from working around the incomplete firmware implementation. We may consider former but for me latter is just insane. -- Regards, Sudeep